The present invention relates to a package structure of a display, and especially to a package structure of a field emission display.
There are many kinds of displays, such as liquid crystal display (LCD), field emission display and plasma display. These displays in accordance with their features are applied in the portable computers, personal digital assistants and color televisions. With the advance of techniques for manufacture and design, these displays have been introduced into the field, and have gradually replaced the CRT used for conventional display.
The structure of a field emission display (FED) is shown in FIG. 1 and includes the cathode plate 122 and anode plate 120. The anode plate 120 includes the upper glass substrate 100 whereon a layer of fluorescence material 102 is deposited. The cathode plate 122 includes the lower glass substrate 110 where the emitter layer 104 is deposited or coated. The side glasses 106 are used to separate the anode plate 120 from the cathode plate 122 by a distance of about 0.5 mm to 2 mm. Photolithography or laser process is used to fix the location of the side glasses 106 on the upper glass substrate 100 or the lower glass substrate 110. Next, glass frits 108 is used to bond the side glasses 106 on the upper glass substrate 100 or the lower glass substrate 110. If the side glasses 106 are bound on the upper glass substrate 100, after aligning the lower glass substrate 110, the glass frits 108 is applied to the adjoining part of the side glasses 106 and the lower glass substrate 100 to adhere them to each other. The two glass substrates 100 and 110 may be adhered to each other by this way.
In the high vacuum situation, when an electric voltage difference exists between the two glass substrates 100 and 110, the field emitting electrons of the emitter 104 are attracted out of the cathode plate 122 and accelerated to hit the fluorescence material 102 of the anode plate 120, causing luminescence. Therefore, after accomplishing the whole package process, an exhausting process must be performed to achieve a vacuum degree lower than the 10xe2x88x926 torr between the two glass substrates 100 and 110. This ensures that the field emitting electrons are not affected by the residual gas thereof. The residual gas may reduce the efficiency of luminescence and the life time of emitters 104.
In the conventional package technology, first, the side glasses 106 are fixed on the upper glass substrate 100 or the lower glass substrate 110. Next, the glass frits 108 is applied to the side glasses 106, after aligning the two glass substrates, to adhere one to the other to finish the package process. However, because the glass frits is used on the two ends of the side glasses 106, at least the following drawbacks exist in the conventional package process:
(1) If the glass frits 108 is not uniformly applied to the side glasses 106, stress may cause the two glass substrates to break during the package process.
(2) After the package alignment process is finished, the whole structure undergoes a thermal cyclecycle. The glass frits 108 is in a fusion state during the thermal cyclecycle. If the glass frits 108 is not uniformly applied to the side glasses 108, the two glass substrates 100 and 110 may shift by shear stress, resulting in misalignment.
(3) Even if the misaligned glass substrates pass safely through the thermal cycle, the probability of breakage during use will increase due to the non-uniform glass frits 108
It is difficult to apply the glass frits uniformly to the side glasses in the conventional package method of the field emission display. As a result, the following processes will be affected. For example, in the process of aligning the two-glass substrates package process, the non-uniform glass frits may cause the two glass substrates to break. If the package alignment process is finished, misalignment between the two glass substrates usually happens because the non-uniform glass frits causes the two glass substrates to slide in the subsequent thermal cycle. Even after the thermal cycle, the non-uniform glass frits increases the breakage probability of the two glass substrates during use because of residual stress. Therefore, the main purpose of the present invention is to provide a package structure of the field emission display to resolve the foregoing drawbacks.
In accordance with the foregoing purpose, the present invention discloses a package structure of field emission display. In accordance with the present invention, first, photolithography or laser process is used to fix the location of the side glasses on the anode plate and the cathode plate. When performing package process, the side glasses are used to separate the anode plate from the cathode plate by a distance. After the alignment process, the glass frits is used to fill the gap between the side glasses respectively belonging to the anode plate and the cathode plate. Next, the whole structure undergoes a thermal cycle at a temperature of about 300 to 450xc2x0 C. Through the thermal cycle the side glasses are adhered to each other by the glass frits so that the anode plate and the cathode plate may be sealed. When a electric voltage difference exist between the two plates, the electrons of the cathode plate are attracted out of the plate and are accelerated to hit the fluorescence material of the anode plate to cause luminescence in vacuum environment.